Sequence Asking Out Of Box Thinking

Can you find what's next in this series?

1, 4, 11, 20, 31, 44, 61, ?


Not getting any clue, here I extend it little further.

1, 4, 11, 20, 31, 44, 61, 100, 121, 144, ? 

Now find what's next.

Note : This needs out of box thinking.

Out of Box Thinking

Couldn't find? Here is the answer! 

This Is Out Of Box Thinking!

Why it was needed?

I said earlier this needs some out of box thinking.

If you carefully observe the digits in the series you won't find any digit exceeding 7 or 8. From that you have to conclude the series must be in octal (number system to base 7 is uncommon).

The series can be represented as,

(x + 1) ^2    ...........where x varies from 0,1,2,3,4,5,6,7,10........

And it's in octal number system.

Out of Box Thought

So the answer is 241.